1. Field of the Invention
The present invention generally relates to a picture signal recording system. More specifically, the present invention is directed to such a picture signal recording system for prohibiting and lawfully permitting duplication (dubbing) of a picture signal, namely for permitting only recording of a live broadcasting picture signal, or only a first recording operation of a signal from a cassette tape.
2. Description of the Prior Art
As a method for prohibiting illegal duplication of a picture signal recorded on a video tape, it has been proposed that an antipiracy signal is assembled in a synchronization signal portion in, for instance, a commercial purpose VTR, which indicates that such a signal duplication is prohibited.
However, the method for assembling the antipiracy signal into the synchronization signal portion has such a problem that this antipiracy signal is readily released by substituting this synchronization signal portion by another synchronization signal portion.
Another method for prevent illegal duplication of a picture signal has been proposed that an antipiracy signal having a frequency higher than the frequency band of the picture signal is superimposed on the picture signal. This method has few problem that a quality of an image reproduced at a TV monitor apparatus is deteriorated, since the antipiracy signal is present at the frequency region higher than the frequency region higher than the frequency band of the picture signal. However, this method can prevent effectively such an illegal duplication by employing a lowpass filter having a simple circuit arrangement to easily remove the antipiracy signal.
Although many other conventional duplication preventing methods have been proposed, no effective method has been proposed without deteriorating the quality of the reproduced image when the picture signal is reproduced under the normal mode.
The applicants of the present invention have been considered the above-described problems, and have provided a picture signal process apparatus for superimposing such an antipiracy signal on a picture signal, which can be hardly removed or canceled, without substantially deteriorating image qualities of the reproduced picture signal in the high-definition television monitor.
The picture signal process apparatus according to the present invention is particularly to prohibit that a picture signal is rerecorded from one video tape to another video tape. In other words, the rerecording operation between the video apparatuses is prohibited.
In these picture signal process apparatuses, the frequency "f.sub.AP " of the antipiracy signal is set to have a frequency interleave relationship with respect scanning to the horizontal scanning frequency "f.sub.H " to defined the horizontal synchronization. The antipiracy signal owns the above-described frequency relationship with the horizontal scanning frequency, and a detectable amplitude to prohibit illegal duplication, and also an amplitude having a level lower than the level at which the reproduced image is not practically deteriorated in the TV monitor apparatus.
As previously stated, even when such an antipiracy signal having the frequency f.sub.AP with the frequency interleave relationship with the frequency f.sub.H, and having the above-described amplitude range is superimposed on the picture signal, there is no practically adverse influence in the reproduced image of the TV screen.
However, there is another problem in an effective operation of a video apparatus if the recording operation to the recording medium such as video tapes is continuously prohibited. In other words, in addition to the above-described method for completely prohibiting the duplication from the video tape, there is specific case that only one recording operation is permitted.
For instance, there is such a need that although a live picture signal having a high image quality of a high-definition television broadcasting system may be once recorded on a video tape, when the picture signal dubbing from this recorded video tape is prohibited, a content of a cassette tape is once permitted to be recorded on the video tape, but the rerecording operation of the contents of this video tape is prohibited.
There is neither an apparatus, or a system capable of satisfying the above-described need in prior art.
Therefore, the present invention has an object to provide a picture signal recording system capable of satisfying such a need.